During the last couple of decades, wheelchairs suitable for action or sports use, such as playing basketball, tennis and other activities, have come into use. The chairs are characterized by their light weight and adjustable wheels. The wheels can be adjusted so that their camber can be changed from 0.degree., that is, with the rear, driving wheels located in a vertical plane, to 12.degree., or sometimes more, where the top of the wheel is closer to the chair than the bottom of the wheel. By changing the camber on the drive wheels, height of the front caster wheels also needs to be changed to adjust the toe in or toe out of the drive wheels as well as to keep the main pivot axis of each of the caster wheels vertical.
With conventional sport or action chairs, the camber adjustment takes the user a significant amount of time. Adjusting the camber often requires removing quite a number of parts and adding or subtracting washers or other spacers to achieve the proper angle. Even when done by a trained technician, the process still takes considerable time. It is a cumbersome, time-consuming job, and requires use of wrenches to torque the nuts to proper tightness. During this procedure, in which two washers typically represent 3.degree. of camber, it is easy to lose washers and to mount the wrong number of washers to the mounting bolt, requiring the job to be redone.
Wheelchairs come in different heights primarily to accommodate the different lengths of the user's legs. This creates a problem for organizations that must supply wheelchairs to a number of individuals, such as wheelchair rental companies, hospitals and nursing homes. Because of different height requirements, a great number of wheelchairs must be kept in stock to accommodate various users. A number of wheelchairs have been designed so that the height of the main drive wheels can be adjusted in various ways. However, these designs generally require some sort of disassembly of the mounting components using tools, an often cumbersome and time-consuming process.